An integrally bladed rotor for gas turbine engines has a plurality of blades with airfoil surfaces radially extending from a disc. The process of joining the individual blades to the disc can result in a mismatch between, for example a top blade portion and a bottom portion which is part of the disc. This mismatch on each blade and root block (which is used to hold the blade during the joining process) must be machined out. However, the tool path designed for this machining operation is defined in a nominal mode, provided for example in a CAD (Computer Aided Design) file. Use of the nominal tool path to direct machining of the integrally bladed rotor with mismatched finished blades, may result in damage to the blades of integrally bladed rotor because differences exist between the nominal profile and an actual profile of the respective blades due to fabrication tolerances and positioning tolerances of the blades. In the prior art, damage is prevented by measuring each individual blade at the joining process and then manually correcting the nominal tool path for machining of each blade. This requires a considerable amount of time and effort sending the part for measurement then re-programming to suit the actual profile of each blade. Furthermore, the conventional measurement method is limited to determining a small number of points along a single line of the actual blade surface at the time of the joining process, for example through touch probing. The adjustment of the nominal tool path is conducted along this line of measured points. However, blades are in a twisting configuration and many lines of points must be measured in order to optimize the tool path for removal of a minimal amount of material after the joining process.
Accordingly, there is a need to provide an improved method of machining an integrally bladed rotor.